[B._Beckhoff,_et_al.]_Handbook_of_Practical_X-Ray_(b-ok.org).pdf

Or ir spectroscopy giving additional structural and

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or IR spectroscopy giving additional structural and molecular information at different structural levels have to be performed in order to get reliable and complementary information on the different materials. The technological developments of the last ten years raised in a revolution- ary manner the number of possible XRF applications in art and archaeology and the potential of information that can be deduced from XRF studies. The most promising perspectives for the determination of new criteria of prove- nance, of manufacturing and (indirectly) of dating are the increased use of mi- crofocus beamlines at synchrotron facilities for archaeometric studies, analyses with “routine” mobile microspectrometers permitting a better knowledge of the material used for many museum objects and the application of confocal 3D micro-XRF. In contrast to the rapid improvement of the XRF devices, at the moment, there is still a lack of quantification procedures that are accurate, flexible, and easy to use. Especially for laboratory micro-XRF set-ups where usually the polychrome spectrum leaving a polycapillary is used for excitation, reli- able standard-bound and standardless quantification routines have still to be established. Hopefully, this drawback will be overcome in the not too distant future. 7.8 XRF-Application in Numismatics J. Engelhardt 7.8.1 Introduction The object coin appears in history at approximately 700 BC and is still to be found in large quantities. Very early, numismatists were interested in the composition of their coins. The composition of coins can provide information on the alloy employed, melting technology, mints, dating, relative metallic
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Methodological Developments and Applications 701 values and the melting down of previously struck coins. The analyses also allow correlating variations in alloy composition with debasement and distinguishing imitations from authentic specimens. Section 7.8.7 provides some examples on how XRF was used to solve the above-mentioned tasks. In the last centuries only wet chemical analysis (WCA) [622] was avail- able so there emerged the need for a nondestructive, fast and simple method. The nondestructive nature of XRF investigations offers this simple and fast method. Since 1950, every type of XRF device (WDXRF [623, 631] EDXRF [624], EDAX [659], PIXE [625], SEM/EDX [626]) has been used to investigate coin compositions with variant success. Though XRF investigations compete with other methods such as neutron activation analysis (NAA) [627], proton activation analysis (PAA) [628] and WCA, the XRF methods are validated by use for investigation into coins (see Carter et al. [629] who compared six methods and see Sect. 7.8.6). Precau- tions due to the surface structure of the coin have to be considered for coin investigations with XRF (see Sect. 7.8.3).
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